Such an actuating device is suitable, to a special degree, for the adjustment of lift-variable valve drives of internal combustion engines and its principle function emerges, for example, from DE 10 2004 021 376 A1. The lift variability of this valve drive is based on a cam part with two cams that are arranged directly adjacent to each other on this cam part and the different opening profiles of these cams are transferred selectively to a gas-exchange valve by a cam follower with a conventionally rigid construction. For the operating point-dependent setting of these opening profiles, the cam part is arranged locked in rotation, but longitudinally displaceable on a carrier shaft and has two spiral-shaped displacement grooves running in opposite directions and in which the end sections of the actuator pins of two actuating devices are selectively coupled (with only one actuator pin). While the axial profile guides the displacement groove engaged with the associated actuator pin such that the cam part shifts in a self-controlling and camshaft angle-true manner from one cam position into the other, the radial profile of each displacement groove is shaped so that this becomes increasingly flatter at the end of the displacement process and displaces the currently engaged actuator pin from its working position back into the rest position.
In the case of the valve drive proposed in DE 196 11 641 C1 with three adjacent cams and two actuator pins arranged at a slight distance, it appears preferable to integrate the actuator pins in a common housing.
An actuating device with a group of actuator pins that are displaceable independently from each other and are supported in a common housing and interact with locking pins loaded by the application of electromagnetic force in the way mentioned above follows from DE 10 2006 051 809 A1, which is considered to be class-forming. The application of electromagnetic force by the locking pins takes place through the use of magnetic armatures that are mounted on these pins and each of which forms an electric lifting magnet. Thus, in the case of two actuator pins, two such electric lifting magnets are required with corresponding high effort for production and assembly of the actuating device.
This consideration relates in the same way for an actuating device according to DE 10 2007 024 598 A1 if a group of actuator pins should be combined in a common housing.
In WO 03/021612 A1, an actuating device is proposed whose actuation is based on the interaction of an electromagnet with a permanent magnet mounted on the actuator pin. Due to its force of magnetic attraction, the actuator pin loaded by the application of spring force in the extension direction attaches to the non-energized electromagnet. For detaching the actuator pin from this rest position, only one application of a pulse-shaped current of the electromagnet is required for overcoming the force of magnetic attraction of the permanent magnet, wherein the actuator pin is accelerated in the direction of the working position not only by the force of the spring means, but also by the force of a magnetic repulsion effect between the permanent magnet and the energized electromagnet.
A structural refinement of this functional principle is disclosed in DE 20 2008 008 142 U1. The actuator pin is held there on a permanent magnet merely by the force of magnetic attraction, so that through mutual eccentric arrangement of actuator pins and permanent magnet/electromagnet, a compact construction of the actuating device is made possible with two or three actuator pins in a common housing.
Apart from the common housing, all of the mentioned actuating devices with multiple actuator pins require a considerable effort of fabrication and assembly, because cost-related synergy effects are produced mainly only by the common housing.